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Subdomain Finder

Discover subdomains for any domain using DNS enumeration. Map your attack surface and find hidden services, staging environments, and forgotten servers.

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Why Subdomain Discovery Matters

Subdomain enumeration is a fundamental reconnaissance technique used in security assessments. Every subdomain represents a potential entry point into your infrastructure — a web application, API endpoint, mail server, or administrative panel that could be targeted by attackers.

Organizations often accumulate subdomains over time as teams spin up development servers, staging environments, testing platforms, and temporary services. Many of these are forgotten but left running, creating shadow IT risks. Unpatched, unmonitored services are prime targets for exploitation.

Regular subdomain auditing is a best practice recommended by security frameworks like NIST and CIS Controls. By knowing exactly what subdomains exist for your domain, you can ensure each one is properly secured, monitored, and decommissioned when no longer needed. This tool uses DNS-based enumeration to check common subdomain names and report which ones are active.

Combine subdomain discovery with tools like our DNS lookup to investigate specific records, or run a full domain security report to audit your email authentication and server configuration.

Frequently Asked Questions

What is subdomain enumeration?
Subdomain enumeration is the process of discovering subdomains that belong to a domain. It involves querying DNS for common subdomain names (like www, mail, ftp, dev, staging) to see which ones resolve to IP addresses. This helps map out all the services and servers associated with a domain.
Why should I scan for subdomains?
Subdomain scanning helps identify forgotten or abandoned services that may have security vulnerabilities, discover shadow IT assets you didn't know existed, audit your attack surface before an attacker does, find development or staging environments that may be exposed to the internet, and verify that your DNS hygiene is clean.
Is subdomain enumeration legal?
Querying DNS records is a normal part of how the internet works and is generally legal. DNS is a public protocol, and looking up subdomains is similar to looking up a phone number in a directory. However, you should only perform security assessments on domains you own or have explicit authorization to test. Using discovered subdomains to attempt unauthorized access is illegal.
What is an attack surface?
An attack surface refers to all the points where an attacker could try to enter or extract data from your systems. Each subdomain represents a potential entry point — it may host a web application, API, mail server, or other service. The more subdomains you have, the larger your attack surface. Regularly auditing your subdomains helps reduce risk by identifying services that should be decommissioned or hardened.
How many subdomains does this tool check?
This tool checks a curated wordlist of the most common subdomain names including www, mail, ftp, dev, staging, api, admin, blog, shop, and many more. While it won't find every possible subdomain (there are infinite possibilities), it covers the most commonly used names that are most likely to be active and relevant for security assessments.

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